Vitamin A deficiency is one of a variety of interrelated risk factors for bronchopulmonary dysplasia in very low birth weight (VLBW) infants. This is a large multicenter clinical trial in VLBW infants at high risk for chronic lung disease (CLD) to evaluate whether vitamin A supplementation in physiologic doses will prevent or reduce the severity of CLD. (This is a NICHD Neonatal Research Network Trial.)